In today's "Closer look," can one senator help the republican party broaden its base? Tim Scott of South Carolina is the first african-american republican from the south since reconstruction. The first black republican in over three decades. He has a message for his party. Jeff Zeleny went on the road with Scott in Charleston. Reporter: Tim Scott is happy to be back home in south Carolina. Up high. Reporter: Giving high fives. Down low. Reporter: Posing for selfies. In every audience. Hamming it up. This is my cousin. Look at this. Reporter: For five years, he's been on a rocket ride. Rising from the Charleston county council to the house of representatives. We caught up with him on the start of the five-week summer break. Leaving a whole list of things unresolved. It's a hard question to wrestle with. How to be compassionate to people that you know are coming to your borders looking for a better way of life, and, at the same time, adhering to the laws of the country. Reporter: Congress has two months to deal with this and nothing. Walked away with absolutely nothing. Is it not a crisis anymore? It's not a crisis that occurred in the last two months. The lack of collaboration. And to show up in the 23rd hour saying, we need you to approve a $4 billion package is not the way to do it. Reporter: He was appointed to the senate a year and half ago, arriving just in time for one of the least productive periods in memory. Whether you're a republican or democrat, you look at the senate and you say to yourself -- you shake your head. Reporter: Scott is brimming with optimism. And steeped in history. He's not only the lone republican african-american in congress. But the only black republican senator in more than a century. I noticed a headline in south Carolina's biggest newspaper earlier this year. It says the gop hopes Tim Scott will attract more black voters. Do you think you have done that? I hope I have provided an opportunity to have a serious conversation with voters everywhere. White voters, black voters, old voters, young voters. Reporter: Why do republicans struggle to diversify they ranks? We need to win the war of ideas. Reporter: Black republicans are a rare find here in south Carolina. Black democrats are skeptical of his politics. It's always good to have diversity. But des diversity can be skin color and it can be philosophy. I would hope that the republican party would be a little more diversified in this approach to the governance. Reporter: Scott says republicans should spend more time focusing on poor and middle class Americans. Have republicans, as a party, though, focused enough on these issues? I think there's always room for improvement. Without any question. One of the things I said consistently is we have to play in the education space. My life has changed because of public education. Reporter: Scott grew up on this dead-end street in north Charleston. He thinks of this neighborhood when he gets hate mail or hears condemnations like when a north Carolina naacp leader called him the gop's ventriloquist dumbny. Do they know you grew up here? At the end of the day, very few of them have taken the time to make a phone call, have a conversation, a debate about my agenda. The truth of the matter is, they have no clue who I am, what I stand for. 15 unelected bureaucrats. Reporter: Conservatives are beaming about their new senator, in part because of his opposition to the president's policies. He's a core conservative. He articulates what he believes. He resonates well with south Carolina republicans. And back here we have -- Reporter: Along the way, Scott started an unusual program. The undercover senator. One of his stops, a burrito restaurant, sweeping floors and chopping chicken to anonymously listen to voters' concerns. Did anyone have an idea you were a United States senator? No. Within an hour, an hour and a half or so, typically, someone says, aren't you that guy? No, I'm not Darius Rucker. I'm just Tim Scott. Reporter: These days, he's putting on his salesman's hat for the gop, trying to sell a hopeful message and soften a debate he says is too often inflammatory and shrill. Do you ever feel like you would like to turn the volume down on some of those senators on both sides of the floor? Yes, just to be blunt, yes. Reporter: Whose microphone? I can't be that blunt. Reporter: Scott's election in November seems almost assured. It's his next chapter that is still to be written. There you go. Reporter: For "This week," Jeff Zeleny, ABC news,

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